Change bigint to integer in Postgres schema grammar.

Bigint has too big a range to be returned as an int in PHP. It is returned as a string, which can be confusing and lead to unexpected results. In addition, the range of integer is suitable for most cases: -2147483648 to +2147483647.
Updated unit tests.
Update src/Illuminate/Database/Schema/Grammars/PostgresGrammar.php
Update src/Illuminate/Database/Schema/Grammars/PostgresGrammar.php
Add support for calculated attributes which aren't stored in the database. Fixes #40
Adding HAVING support to the query builder.

Signed-off-by: Ben Corlett <bencorlett@me.com>
Merge branch 'master' of git://github.com/illuminate/database
Test passing multiple parameters to with().
Allow passing multiple parameters to with().
Allow fluent access when adding collection elements.
Test fluent interface when adding elements.
test the collection->load method.
fix bug in sync methods.
keep an array of the original attributes.
tweak how migrations work for packages.
fix typo.
make migration provider deferred.
make seed service provider deferred.
Fixed typos
Fixes issue with default connection in ConnectionResolver.php

Signed-off-by: Alexander Cogneau <alexander.cogneau@hotmail.be>